Hydrophobic silica aerogels for oil spills clean-up, synthesis, characterization and preliminary performance evaluation

Abstract

The most important requirements for surface water management include the availability of rapid and efficient specific adsorbents. This work presents synthesis, characterization and performance analysis of a novel silica aerogel for oil decontamination from surface water. Hydrophobic silica aerogel powders were synthesized by a rapid co-precursor method applying ambient pressure. An inexpensive aqueous sodium silicate solution was used as starting material, with hexamethyldisilazane (HMDS), tetraethyl orthosilicate and trimethylchlorosilane as organic co-precursors. The prepared silica aerogels were characterized by nitrogen adsorption/desorption technique (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and contact angle measurements. Silica aerogel samples prepared using HMDS exhibited the highest BET surface area of about 936 m2/g, pore volume (1.715 cm3/g) and contact angle approaching 106°. The aerogels were then tested for oil adsorbing capacity in oil salt–water mixtures for oil spill clean-up applications. Preliminary oil adsorption experiments have shown that a maximum oil removal of 96 and 90 % using silica aerogel prepared from HMDS from saline and non-saline oily waste waters, respectively. Moreover, the minimization of the costly precursors permits a low-cost large scale production and economic oil spill clean-up applications.